Bleaching compositions

ABSTRACT

Hypochlorite bleaching compositions comprise a phosphate ingredient, for improved fabric whiteness and improved fabric safety.

FIELD OF THE INVENTION

The present invention relates to bleaching compositions, in particularto hypochlorite bleaching compositions, suitable for use in laundryapplications such as hand and machine laundry methods.

BACKGROUND OF THE INVENTION

Bleaching compositions are well-known in the art. Amongst the differentbleaching compositions available, those relying on bleaching byhypohalite bleaches such as hypochlorite are often preferred, mainly forperformance reasons, especially at lower temperature.

However, a problem encountered with the use of hypochloritebased-compositions is the resulting damage and/or yellowing of thefabrics being bleached.

It is therefore an object of the invention to provide ahypohalite-containing composition, suitable for use in laundryapplications, which provides improved fabric whiteness to fabricstreated therewith.

It is another object of the invention to provide a hypohalite-containingcomposition, suitable for use in laundry applications, which providesimproved fabric safety to fabrics treated therewith.

The Applicant has thus now surprisingly found that this problem issolved by the provision, in a hypohallite bleaching composition, of aphosphate ingredient. Indeed, it has been found that improved fabricwhiteness and/or safety were obtained with the composition of theinvention compared to hypohalite compositions without said phosphateingredient. The benefits are particularly noticeable in hypohalitebleaching compositions which further comprise a pH buffering component.

Another advantage of the compositions of the invention is that they arechemically stable. By “chemically stable”, it is meant that thehypohalite bleaching compositions of the present invention should notundergo more than 15% loss of available chlorine after 5 days of storageat 50° C. ±0.5° C. The % loss of available chlorine may be measuredusing the method described, for instance, in “Analyses des Eaux etExtraits de Javel” by “La chambre syndicate nationale de L'eau de Javelet des produits connexes”, pages 9-10 (1984). Said method consists inmeasuring the available chlorine in the fresh compositions, i.e. justafter they are made, and in the same compositions after 5 days at 50° C.

A further advantage of the compositions of the invention is that theyare suitable for the bleaching of different types of fabrics includingnatural fabrics (e.g., fabrics made of cofton, viscose, linen, silk andwool), synthetic fabrics such as those made of polymeric fibers ofsynthetic origin as well as those made of both natural and syntheticfibers. Indeed, the compositions of the present invention may be used onsynthetic fibers despite a standing prejudice against the use ofhypohalite bleaches, especially hypochlorite bleaches, on syntheticfibers, as evidenced by warning on labels of commercially availablehypochlorite bleaches and clothes.

EP 0 188 145 discloses bleaching compositions comprising trisodiumphosphate. J53081789 discloses compositions comprising hypochlorite anda phosphate ingredient for the cleaning of carpets. J03137278 disclosesa composition comprising hypochlorite and a phosphate ingredient for thebleaching of indigo-dyed cloth. J08081878 discloses bleachingcompositions with a phosphate ingredient for the bleaching of rawtextiles. None of these prior art documents discloses the fabricwhiteness and safety benefits obtained from the provision of a phosphateingredient in a hypochlorite composition.

SUMMARY OF THE INVENTION

The present invention is a liquid or solid bleaching compositioncomprising

a hypohalite bleach,

a pH buffering component in an amount of 0.5% to 9% by weight, and

an effective amount of a phosphate ingredient.

The present invention also encompasses a process of treating fabricswhere said fabrics are immersed in a bleaching solution formed bydiluting said bleaching composition in water.

The present invention further encompasses the use, in a hypohalitebleaching composition, of a phosphate ingredient, for providing improvedfabric whiteness and/or safety to the fabrics treated therewith.

DETAILED DESCRIPTION OF THE INVENTION

Hypohalite bleach

An essential component of the invention is a hypohalite bleach.Hypohalite bleaches may be provided by a variety of sources, includingbleaches that are oxidative bleaches and subsequently lead to theformation of positive halide ions as well as bleaches that are organicbased sources of halides such as chloroisocyanurates.

Suitable hypohalite bleaches for use herein include the alkali metal andalkaline earth metal hypochlorites, hypobromites, hypoiodites,chlorinated trisodium phosphate dodecahydrates, potassium and sodiumdichloroisocyanurates, potassium and sodium trichlorocyanurates,N-chloroimides, N-chloroamides, N-chloroamines and chlorohydantoins.

For liquid compositions, the preferred hypohalite bleaches among theabove described are the alkali metal and/or alkaline earth metalhypochlorites selected from the group consisting of sodium, potassium,magnesium, lithium and calcium hypochlorites, and mixtures thereof, morepreferably the alkali metal sodium hypochlorite.

For solid compositions, the preferred hypohalite bleaches among theabove described are the alkali metal and/or alkaline earth metalhypochlorites selected from the group consisting of lithiumhypochlorites, calcium hypochlorites, chlorinated trisodium phosphatedodecahydrates, potassium dichloroisocyanurates, sodiumdichloroisocyanurates, potassium trichlorocyanurates, sodiumtrichlorocyanurates, and mixtures thereof, more preferably sodiumdichloroisocyanurates and/or calcium hypochlorite. Preferably, theliquid compositions according to the present invention comprise saidhypohalite bleach such that the content of active halide in thecomposition is of from 0.1% to 20% by weight, more preferably from 2% to8% by weight, most preferably from 3% to 6% by weight of thecomposition. Preferably, the solid compositions according to the presentinvention comprise said hypohalite bleach such that the content ofactive halide in the composition is of from 20% to 95% by weight, morepreferably from 25% to 60% by weight of the composition.

pH buffering component

A pH buffering component is another essential component for thecompositions of the invention. The pH buffering component ensures thatthe pH of the composition is buffered to a pH value ranging from 7.5 to13, preferably from 8 to 12, more preferably from 8.5 to 11.5 after thecomposition has been diluted into 1 to 500 times its weight of water.

Suitable pH buffering components for use herein are selected from thegroup consisting of alkali metal salts of carbonates, polycarbonates,sesquicarbonates, silicates, polysilicates, borates, metaborates,phosphates, stannates, alluminates and mixtures thereof, and preferablyare selected from the group consisting of sodium carbonate, sodiumsilicate, sodium borate, and mixtures thereof.

The raw materials involved in the preparation of hypohalite bleachesusually contain by-products, e.g calcium carbonate resulting in anamount of up to 0.4% by weight of by-product within the hypohalitecomposition. However, at such amount, the by-product will not have thebuffering action defined above.

Liquid bleaching compositions herein will contain an amount of pHbuffering component of from 0.5% to 9% by weight, preferably from 0.5%to 5% by weight, and more preferably in an amount of from 0.6% to 3% byweight of the composition.

Solid bleaching compositions herein will preferably contain an amount ofpH buffering component of from 3% to 30% by weight, more preferably from5% to 25% by weight, and most preferably in an amount of from 10% to 20%by weight of the composition.

The Phosphate ingredient

Phosphonic acid can be condensed in the reaction

The reaction can be repeated with any of the reactive OH groups, andphosphate ingredients are obtained which can be

linear or branched polyphosphates of structure

 when R is M or

 when M is a counterion, preferably alkali metal;

when 0 ≦n+m<500 (if n+m=0 then the compound is phosphonic acid)

cyclic polyphosphates (also referred to as metaphosphates), of structure

 where R is M or

if R is

 OR

the phosphate compound contains both cycles and branched-chain, and canbe referred to as an ultraphosphate.)

where M is a counterion, preferably an alkali metal

where O≦n+m<500

All such phosphate ingredients are suitable for use herein, andpreferred are linear phosphate ingredients (i.e. R is M) where n is 1(pyrophosphate) and n is 2 (tripolyphosphate), most preferably where nis 2. The most commonly available form of these phosphate is where M isSodium.

The phosphate ingredients herein are present in amounts of from 0.001%to 20%, preferably 0.005% to 5%, most preferably 0.005% to 1% by weightof the total composition. Of course, mixtures of different phosphateingredients can be used.

The whitening effect, i.e. the yellowing-prevention effect, and/orsafety effect of the present invention can be evaluated by comparing thecomposition according to the present invention to the same compositionwithout the phosphate ingredient.

The degree of yellowing can be determined by both visual and instumentalgrading. Visually, the difference in yellowing between items treatedwith different compositions can be determined by a team of expertpanellists. Instrumentally, the assessment can be determined with thehelp of Colorimeters such as Ganz Griesse® instruments (e.g., Datacolor®Spectraflash® SF 500, Machbet White-eye®) 500) or a ZEISS ELREPHO® orothers which are available for instance from HunterIab®) or Gardner®.

Fabric safety may be evaluated by different test methods including thedegree of polymerisation test method according to UNI (Ente NazionaleItaliano di Unificazione) official method UNI 8282-Determinazione. dellaviscosita intrinseca in soluzione di cuprietilendiammina (CED).

The compositions according to the present invention are either in liquidor solid form. Solid forms include forms such as powders, tablets andgranules. Preferably, the compositions of the invention are in liquidaqueous form. More preferably, they comprise water in an amount of from60% to 98% by weight, more preferably of from 80% to 97% and mostpreferably of from 85% to 97% by weight of the total aqueous liquidbleaching composition.

pH

The pH of the liquid compositions according to the present invention, asis, is typically from 12 to 14 measured at 25° C. Solid compositions orliquid compositions of the invention have a pH of from 7.5 to 13,preferably from 8 to 12, more preferably from 8.5 to 11.5, when dilutedinto 1 to 500 times its weight of water. It is in this alkaline rangethat the optimum stability and performance of the hypohalite as well asfabric whiteness and/or safety are obtained. The pH range is suitablyprovided by the pH buffering component and the hypohalite bleachmentioned hereinbefore, which are alkalis. However, in addition to thesecomponents, a strong source of alkalinity may also optionally be used.

Suitable sources of alkalinity are the caustic alkalis such as sodiumhydroxide, potassium hydroxide and/or lithium hydroxide, and/or thealkali metal oxides such as sodium and/or potassium oxide. A preferredstrong source of alkalinity is a caustic alkali, more preferably sodiumhydroxide and/or potassium hydroxide. Typical levels of such causticalkalis, when present, are of from 0.1% to 1.5% by weight, preferablyfrom 0.5% to 1.5% by weight of the composition.

Optional polymers

An optional component of the compositions herein is a polymer. Thatpolymer, has surprisingly been found to also reduce the yellowing of thefabrics treated therewith, i.e. improve whiteness, as well as improvefabric safety. Naturally, for the purpose of the invention, the polymerhas to be stable to the hypohalite bleach.

Suitable polymers for use are polymers comprising monomeric unitsselected from the group consisting of unsaturated carboxylic acids,polycarboxylic acids, sulphonic acids, phosphonic acids and mixturesthereof. Co-polymerisation of the above monomeric units among them orwith other co-monomers such as styrenesulfonic acid is also suitable.

Preferred examples of such polymers are the polymers and co-polymers ofmonomeric units selected from the group consisting of acrylic acid,maleic acid, vinylsulphonic acid and mixtures thereof. Also suitable foruse herein are the above mentioned polymers and co-polymers which aremodified in order to contain other functional groups such asaminophosphonic and/or phosphonic units. More preferred polymers areselected from the group consisting of polyacrylate polymers, co-polymersof acrylic and maleic acid, co-polymers of styrene sulphonic acid andmaleic acid, and mixtures thereof, preferably modified withaminophosphonic and/or phosphonic groups.

The molecular weight for these polymers and co-polymers is preferablybelow 100,000, most preferably between 500 and 50,000. Most suitablepolymers and co-polymers for use herein will be soluble in an amount upto 0.1% by weight, in an aqueous composition comprising 5% by weight ofsodium hypochlorite with its pH adjusted to 13 with sodium hydroxide.

Commercially available such polymers, suitable for use herein, are thepolyacrylate polymers sold under the tradename Good-Rite® from BFGoodrich, Acrysol® from Rohm & Haas, Sokalan® from BASF, Norasol® fromNorso Haas. Also suitable for use herein are the co-polymers of styrenesulphonic acid and maleic acid, commercially available under thetradename Versaflex® from National Starch such as Versaflex 157, as wellas Acumer® terpolymers from Rohm and Haas, in particular Acumer® 3100.Preferred commercially available polymers are the polyacrylate polymers,especially the Norasol® polyacrylate polymers and more preferred are thepolyacrylate polymer Norasol® 410N (MW 10,000) and the polyacrylatepolymer modified with phosphonic groups Norasol® 440N (MW 4000) and itscorresponding acid form Norasol® QR 784 (MW 4000).

A preferred polymer for use herein is a polyacrylate polymer modifiedwith phosphonic groups commercially available under the tradenameNorasol® 440N (MW 4000) and its corresponding acid form Norasol® QR 784(MW 4000) from Norso-Haas.

Mixtures of polymers as herein described may also be used in the presentinvention.

Polymers herein are preferably present in low amounts, i.e. in amountsof up to 0.5% by weight, more preferably from 0.001% to 0.3% by weight,most preferably from 0.005% to 0.2% by weight of the liquid composition.

The composition according to the invention may also comprise furtheroptional components such as perfumes, bleach-stable surfactants, organicor inorganic alkalis, pigments, dyes, optical brighteners, solvents,chelating agents, radical scavengers and mixtures thereof.

Preferably, the compositions of the invention are used in diluted formin laundry applications. The expression “used in diluted form” hereinincludes dilution by the user, which occurs for instance in hand laundryapplications, as well as dilution by other means, such as in a washingmachine. Preferably, the composition is diluted into 5 to 500 times itsweight of water for hand laundry application and 10 to 500 times itsweight of water in a washing machine. Thus, in another aspect of theinvention, there is provided a process for bleaching fabrics with acomposition as disclosed herein, where said fabrics are immersed in ableaching solution formed by diluting said composition in water.

In yet another aspect of the invention, there is provided the use, in ahypohalite bleaching composition, of a phosphate ingredient forproviding improved whiteness and/or safety to the fabrics treatedtherewith. By “improved whiteness and/or safety”, it is meant thathypohalite bleaching compositions, with the phosphate ingredient,provide better whiteness, i.e. less yellowing, and/or fabric safetycompared to hypohalite bleaching compositions which do not comprise saidphosphate ingredient. In this embodiment, the presence of a pH bufferingcomponent in the bleaching composition is not compulsory, but is highlypreferred.

The invention is illustrated in the following non-limiting examples, inwhich all percentages are on a weight basis unless otherwise stated.

Examples Composition (weight %) 1 2 3 4 Sodium hypochlorite 5.0 5.0 5.02.5 Sodium hydroxide 0.9 0.7 0.7 0.7 Sodium carbonate 1.2 1.2 1.2 1.2Sodium silicate — 0.5 — — Sodium metaborate — — 1.0 1.0 Sodiumtripolyphosphate (STPP)  0.05 0.1 0.5 1   Water and minors up to 100%Composition (weight %) 5 6 7 8 9 Sodium hypochlorite 5.0 5.0 3.5 3.5 5Sodium hydroxide 1 1.5 1 1.5 0.8 Sodium carbonate 1 2 2 1.5 2 Sodiumsilicate — — 0.5 0.5 0.5 Sodium metaborate — — — — — Sodiumtripolyphosphate 0.1 0.05 0.2 0.3 1 Norasol ® 440N — 0.1 — 0.2 —Norasol ® 410N 0.05 0.1 0.1 — 0.1 Water and minors up to 100%

What is claimed is:
 1. A liquid bleaching composition comprising: ahypohalite bleach, a pH buffering component in an amount of 0.5% to 9%by weight, wherein said pH buffering component is selected from thegroup consisting of alkali metal salts of carbonates, polycarbonates,sesquicarbonates, silicates, polysilicates, borates, metaborates,stannates, aluminates, and mixtures thereof; and a fabric whiteingand/or fabric safety enhancing effective amount of a phosphateingredient.
 2. A bleaching composition according to claim 1, whereinsaid pH buffering component is selected from the group consisting ofsodium carbonate, sodium silicates, sodium borate, and mixtures thereof.3. A bleaching composition according to claim 1 wherein said hypohalitebleach is an alkali metal sodium hypochlorite.
 4. A bleachingcomposition according to claim 1 wherein said hypohalite, based onactive halide, is present in an amount of from 0.1% to 20% by weight ofthe liquid composition.
 5. A bleaching composition to claim 1 whereinsaid composition further comprises a strong source of alkalineity.
 6. Ableaching composition according to claim 1 wherein said phosphateingredient is of a structure selected from the group consisting of:linear or branched polyphosphates of structure

 or cyclic polyphosphates (also referred to as metaphosphates), ofstructure

 when M is a counterion, preferably alkali metal; when O≦n+m<500 (ifn+m=0 then the compound is phosphoric acid) and mixtures thereof.
 7. Ableaching composition according to claim 6, wherein said phosphate issodium pyrophosphate or sodium tripolyphosphate.
 8. A bleachingcomposition according to claim 1 wherein said composition comprises fromabout 0.001% to about 20% of said phosphate ingredient.
 9. A bleachingcomposition according to claim 1 wherein said composition furthercomprises a polymer.
 10. A bleaching composition according to claim 7wherein said phosphate is sodium tripolyphosphate.
 11. A process forbleaching fabrics comprising the step of contacting said fabric with ableaching composition according to claim 1.